Ventricular ectopy: etiology, evaluation, and therapy

Characterisation of the dynamic nature of lipids throughout the lifespan of genetically identical female and male Daphnia magna

Lipids play a significant role in regulation of health and disease. To enhance our understanding of the role of lipids in regulation of lifespan and healthspan additional studies are required. Here, UHPLC-MS/MS lipidomics was used to measure dynamic changes in lipid composition as a function of age and gender in genetically identical male and female Daphnia magna with different average lifespans. We demonstrate statistically significant age-related changes in triglycerides (TG), diglycerides (DG), phosphatidylcholine, phosphatidylethanolamine, ceramide and sphingomyelin lipid groups, for example, in males, 17.04% of TG lipid species decline with age whilst 37.86% increase in relative intensity with age. In females, 23.16% decrease and 25.31% increase in relative intensity with age. Most interestingly, the rate and direction of change can differ between genetically identical female and male Daphnia magna, which could be the cause and/or the consequence of the different average lifespans between the two genetically identical genders. This study provides a benchmark dataset to understand how lipids alter as a function of age in genetically identical female and male species with different average lifespan and ageing rate.

Long-term outcome following programmed electrical stimulation in patients with high-grade ventricular ectopy

To determine if programmed electrical stimulation (PES) could be utilized to identify patients with high-grade ventricular ectopy at low- or high-risk for sudden cardiac death, we performed PES in 40 patients with high-grade ventricular ectopy refractory to conventional antiarrhythmic agents. Twenty-one patients had a previous myocardial infarction, five had cardiomyopathy, six had hypertension, three had valvular heart disease and five had no known structural heart disease. The mean age was 50 years (range, 18 to 76). During programmed ventricular stimulation, eight patients had inducible sustained (more than 30 seconds) monomorphic ventricular tachycardia (Group I) but in 32 patients sustained ventricular tachycardia was not inducible (Group II). None of the five patients without structural heart disease were inducible while seven out of 21 (33%) patients with previous myocardial infarction had inducible ventricular tachycardia (VT). Antiarrhythmic therapy was instituted in patients with inducible VT; patients without inducible VT did not receive antiarrhythmic agents. In Group I, seven of the eight patients are alive (mean follow-up, 16 months) and in Group II, 28 of the 32 patients are alive (mean follow-up, 17 months). None of the five deaths were sudden. We conclude that in the absence of antiarrhythmic therapy, the incidence of sudden cardiac death is very low in patients with high-grade ventricular ectopy who do not have inducible monomorphic ventricular tachycardia during programmed ventricular stimulation.

The incidence of prebypass dysrhythmias in patients undergoing coronary artery surgery

The incidence of dysrhythmias during the prebypass period of coronary artery surgery has not been accurately reported. Using Holter monitoring of the electrocardiogram, this study was undertaken to determine the incidence of dysrhythmias and ischemia and their relationship to specific events during the prebypass period. The role of preoperative calcium entry blockers (CEB), beta-adrenergic blockers (BB), or both on the incidence of dysrhythmias and ischemia was also studied. One hundred thirty-eight patients were premedicated with morphine, scopolamine, and diazepam. Anesthesia was induced with fentanyl or sufentanil followed by either pancuronium or vecuronium and maintained with sufentanil or enflurane. All 138 patients experienced a dysrhythmia during the prebypass period. Seventy-five percent of the patients had at least one episode of a supraventricular dysrhythmia (SVD), 39% had a sinus bradycardia, and 20% had a conduction abnormality. Ninety-two percent of the patients had premature ventricular contractions (PVC) and, surprisingly, 76% had non-sustained ventricular tachycardia. One patient developed ventricular fibrillation and one had ventricular tachycardia. The peak incidence of dysrhythmias occurred at insertion of the pulmonary artery (PA) catheter and at aortic dissection. The incidence of prebypass ischemia was 18%, but these patients did not have a higher incidence of ventricular dysrhythmias. Preoperative CEBs and BBs did not influence the incidence of ischemia or dysrhythmias with the exception of SVD; there was a significantly lower incidence at PA catheterization in patients taking CEBs preoperatively (P < .05). It can be concluded that dysrhythmias are very common during the prebypass period. The low rate of progression to life-threatening dysrhythmias may be related to the fact that the majority occurred during mechanical stimulation and that patients were chronically taking CEBs and/or BBs preoperatively.

Low heart rate variability and sudden cardiac death

Our results indicate the following. 1. HRV is markedly depressed in inducible SCD survivors, a group at high risk of a subsequent episode of SCD. 2. Studies on patients who developed SCD during Holter monitoring indicate that HRV is depressed prior to SCD. 3. HRV is markedly depressed in inducible "asymptomatic ventricular ectopy" patients, with the degree of reduction paralleling that observed in inducible SCD survivors. In contrast, HRV of noninducible "asymptomatic ventricular ectopy" patients did not differ statistically from normal. 4. The findings provide additional evidence that cardiac parasympathetic function is depressed in patients prone to development of SCD and that altered autonomic function contributes to the development of electrical instability in such individuals. This accords with findings that such risk factors for sudden death as coronary artery disease, myocardial infarction, congestive failure, and hypertension all have been associated with reduced parasympathetic activity or attenuation of parasympathetically mediated reflexes. It is tempting to believe that diminished cardiac parasympathetic activity, perhaps by failing to counter excess sympathetic activity, contributes to SCD. 5. It may be inferred that HRV measurements have potential for serving as an independent predictor of inducibility in response to programmed ventricular stimulation and that they could represent a noninvasive screen for patients referred for evaluation of risk of SCD because of asymptomatic ventricular ectopy or other causes. In a larger sense, the data suggest that HRV measurements may provide information pertinent to the identification of individuals at increased risk of SCD that is independent of that provided by other risk factors. Given the human and economic stakes, further study is clearly warranted.

Prognostic implications of complex ventricular ectopy in patients with and without structural heart disease. A study based on programmed electrical stimulation

Fifty-six patients with complex ventricular premature beats (Lown grade IVa, IVb), but no evidence of ventricular tachycardia on 48 hours of continuous monitoring were evaluated by programmed electrical stimulation. Thirty patients had coronary atherosclerotic heart disease, 3 had valvular heart disease, 2 had cardiomyopathy and 21 had no structural heart disease. Programmed stimulation identified two groups of subjects: Group I comprised 11 patients in whom ventricular tachycardia was induced and Group II comprised 45 patients (which included 21 patients without heart disease) in whom no ventricular tachycardia was induced. The incidence of left ventricular dysfunction (ejection fraction less than 40%) was significantly higher in Group I as compared to Group II (P less than 0.001). There was, however, no difference between the grade of ventricular ectopy, HV interval or the incidence of bundle branch block between the 2 groups. Patients with inducible ventricular tachycardia (Group I) were put on laboratory directed anti-arrhythmic drug therapy. Patients without inducible tachycardia (Group II) were not given anti-arrhythmic therapy. The patients were followed up for 34 +/- 10 months. The incidence of sudden death (36.3% vs 6.6%, P less than 0.001) was significantly higher in Group I as compared to Group II. No patients without structural heart disease died during the follow-up. Programmed electrical stimulation fails to induce ventricular tachycardia in patients with complex ventricular ectopy but no structural heart disease. It is, however, possible to define a high risk subset in patients with structural heart disease and complex ectopy. The high risk patients with inducible ventricular tachycardia do not seem to benefit by anti-arrhythmic drugs, which may independently increase the risk of sudden death in treated patients. Patients in whom ventricular tachycardia is not inducible have better left ventricular function, a good long-term prognosis and do not require anti-arrhythmic agents.

Clinical intracardiac electrophysiologic testing: technique, diagnostic indications, and therapeutic uses

Clinical cardiac electrophysiologic testing has evolved rapidly since 1968, when the technique was first described. In an electrophysiologic study, electrode catheters are positioned within the heart to record electrical activity from the atrium, atrioventricular conduction tissue, and ventricle. Programmed stimulation is then performed, which involves pacing of the atrium or ventricle and introducing critically timed premature stimuli during sinus rhythm or paced rhythm. The use of programmed stimulation in conjunction with intracardiac recordings in electrophysiologic studies has facilitated the diagnosis of mechanisms of arrhythmias and the assessment of therapy. Electrophysiologic testing is useful in selected patients with sinus node dysfunction, conduction system disorders, supraventricular tachycardia, ventricular tachycardia, or ventricular fibrillation and in survivors of out-of-hospital cardiac arrest and patients with symptomatic but unsubstantiated rhythm disturbances. Therapeutic approaches that can be assessed by electrophysiologic testing include serial drug testing to determine the effectiveness of antiarrhythmic agents, antitachycardia pacing, the implantable defibrillator, transcatheter ablation, and electrophysiologically guided surgical procedures. In this review, we discuss the methods of electrophysiologic testing, its clinical applications in diagnosing the various cardiac rhythm disturbances, and its use in assessing various therapeutic modalities.

Effects of first-dose doxorubicin on cardiac rhythm as evaluated by continuous 24-hour monitoring

Doxorubicin has been reported to cause ventricular arrhythmias and sudden death in the first 24 hours after administration. The authors placed continuous electrocardiographic recording devices on 30 patients 24 hours before, during, and 24 hours after doxorubicin administration. Nine patients experienced arrhythmias before treatment; 12 patients had posttreatment ectopy. No patient had life-threatening arrhythmias before or after treatment. Of the nine patients with pretreatment ectopy, only one experienced an increase in severity. Conversely, six patients without ectopy before treatment had arrhythmias after doxorubicin administration. The authors were unable to determine predictive factors in patients with no pretreatment ectopy who developed posttreatment premature ventricular contractions. The authors conclude that antecedent ventricular ectopy exists in the oncologic population and that this is not worsened by first-dose exposure to doxorubicin.

Incidence and causes of hypokalemia associated with cardiac resuscitation

To further investigate the incidence and etiology of hypokalemia during cardiac arrest, the authors compared data on 74 adult nontrauma cardiac arrest patients (44 men, 30 women, age 65 +/- 13 years) who had a serum potassium (K+) level documented during or immediately following resuscitation with data on 53 adult controls with life-threatening medical emergencies presenting to the emergency department who did not experience arrest. Hypokalemia (serum K+ less than 3.6 mEq/l) occurred in 25 arrest patients (34%) compared with nine controls (17%). Serum K+ was not significantly different shortly before (3.7 +/- 0.4) versus immediately after arrest (3.6 +/- 0.8) in a small subgroup of patients, making intracellular shifting of K+ because of metabolic events during resuscitation an unlikely etiology. Hypokalemia was associated with a 2.5-fold increase in relative risk for cardiac arrest. Patients who were receiving diuretics without K+ supplementation had the highest risk of arrest (4.4-fold increase). Supplementation of K+ appeared to be protective in patients on diuretics. The authors confirm the association between hypokalemia and cardiac arrest and suggest that this metabolic abnormality may be an important risk factor for cardiac arrest.

How the university cardiologist treats ventricular premature beats: a nationwide survey of 65 University Medical Centers

Sixty-five of 118 university cardiologists responded to a survey of indications for treatment of ventricular ectopy, particularly in the completely asymptomatic patient or those with palpitations as the only symptom. The percentage of cardiologists treating these patients increased as the complexity of ventricular ectopy increased, as the severity of underlying heart disease increased, as the symptoms increased from completely asymptomatic to palpitations or skipped beats, if the patient experienced dizziness or syncope, and if the patient had complex VPBs or asymptomatic VT after MI. Ninety-eight percent of respondents had patients who experienced exacerbation of arrhythmia with antiarrhythmic drugs. Of the conventional type 1 drugs, the drug of first choice was quinidine for 60%, procainamide for 37%, and disopyramide for 3%. The accepted indications for electrophysiologic testing included survivors of sudden cardiac arrest and patients with symptomatic VT.

Analysis of the spontaneous variability of ventricular arrhythmias: consecutive ambulatory electrocardiographic recordings of ventricular tachycardia

Results are reported of analysis of the variability of complex ventricular arrhythmias in a cohort of 110 patients selected for the presence of ventricular tachycardia (VT). All patients were enrolled in investigational antiarrhythmic drug trials and had an average of 4 consecutive days of placebo ambulatory electrocardiographic recording to serve as the database for this study. Using a statistical approach incorporating analysis of variance, the minimum percent reductions of ventricular premature complexes, couplets and VT were calculated to establish "drug effect" rather than variability at a significance level of 0.05. The relative variability of ventricular arrhythmias in prognostically important groups was also analyzed: (1) coronary artery disease (CAD) (n = 57) vs no CAD (n = 53); (2) patients with a left ventricular ejection fraction of 40% or less (n = 52) vs those with an ejection fraction greater than 40% (n = 58); and (3) patients with frequent runs of VT (10 or more runs/day, n = 63) vs infrequent VT (n = 47). Multiple regression analysis revealed that patients with CAD have significantly greater premature ventricular complex variability than patients without CAD (p less than 0.01). Also, patients with frequent VT runs have greater VT variability than that previously reported in smaller studies, thus requiring greater VT reductions to establish drug effect. Whether the variability of ventricular arrhythmia is itself an independent risk factor for sudden cardiac death is unknown.

Psychosocial aspects of surviving sudden cardiac death

The psychosocial problems faced by the survivor of "sudden cardiac death" are discussed from the point of view of the patient, the family, and the physician. The patient faces a battery of intensive diagnostic tests, as well as concern for future capability to resume function as "spouse, parent, and citizen." Emotions such as depression, anger, anxiety, frustration, and fear must be dealt with in a constructive manner. Management includes education, support, encouragement of adaptive denial, anxiolytic medication if necessary, and relaxation techniques when helpful. Our approach begins with education of the patient and family in regard to the medical aspects of the illness. Next, we provide support for the patient and allow the patient to express his or her concerns at an individual pace. Adaptive denial is encouraged and maladaptive denial addressed. Appropriate medication is prescribed when necessary, and finally, relaxation techniques may have a role in some patients. A strong physician-patient relationship is necessary for successful evaluation and therapy. The unique stresses of the cardiologist and the electrophysiology team are described.

Programmed electrical stimulation in patients with high-grade ventricular ectopy: electrophysiologic findings and prognosis for survival

The significance and treatment of ventricular premature beats (VPBs) in patients without sustained ventricular tachycardia (VT), sudden death, or syncope remains unclear. We undertook a prospective study of programmed electrical stimulation (up to two extrastimuli and burst pacing) in 73 patients (age 60 +/- 10 years) with high-grade VPBs who had no evidence of sustained VT, sudden death, or syncope as determined by 48 hr of monitoring in the cardiac care unit and 48 hr Holter monitoring. Fifty-six patients (76.7%) had atherosclerotic heart disease, 10 (13.7%) had cardiomyopathy or valvular heart disease, and seven (9.6%) had no evident heart disease. Thirty-seven patients (50.7%) had Lown grade IVB VPBs, 30 (41.1%) had Lown grade IVA VPBs, and six (8.2%) had Lown grade III VPBs. Programmed electrical stimulation identified two groups of subjects: group 1 comprised 20 patients (27%) in whom VT or ventricular fibrillation was induced, group 2 comprised 53 patients (73%) in whom no ventricular arrhythmia or only two to four repetitive ventricular responses were induced. There was a significant difference between the presence of atherosclerotic heart disease, old myocardial infarction, and ejection fraction of less than 40% in group 1 compared with group 2. However, there was no significant difference in the grade of VPBs between the two groups. Seventeen of 20 patients from group 1 were placed on antiarrhythmic therapy (defined by programmed electrical stimulation), whereas group 2 patients were randomly assigned to prophylactic antiarrhythmic therapy. A total of 70 patients were followed up for 30 +/- 15 months. The incidence of sustained VT and/or sudden death (31.5% vs 2%; p less than .001) was significantly higher in group 1 compared with group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of lorcainide and quinidine in the treatment of ventricular ectopy

Lorcainide, a new type I antiarrhythmic agent, was compared to quinidine in respect to antiarrhythmic efficacy and clinical safety. Thirteen subjects completed an open, randomized, crossover study with analysis of 24-hour ambulatory ECG monitoring and drug blood levels. The QRS and Q-T intervals increased with both lorcainide and quinidine. The mean reduction in total ventricular premature beats (VPBs) with quinidine was 16 percent compared to 68 percent with lorcainide (p less than .05). With lorcainide eight of 13 subjects had a significant (greater than 82 percent) reduction in VPBs compared to only three of 13 subjects taking quinidine (p less than .05). This same relationship was observed when mean VPB/1,000 heartbeats was analyzed. Ventricular tachycardia was no longer present in five of nine subjects taking lorcainide and in two of nine taking quinidine. No relationship could be established between drug level and arrhythmia suppression in this small population. Some CNS effects were reported in both groups, but no significant hematologic, chemical, or urinary adverse effects were seen with either drug. Thus, lorcainide compares favorably to quinidine in regard to arrhythmia suppression, but was limited in its clinical utility by CNS side effects.

A controlled trial of propafenone for treatment of frequent and repetitive ventricular premature complexes

The effectiveness of oral propafenone was evaluated for the treatment of ventricular premature complexes (VPCs) in 12 patients, using a single-blind, dose-ranging trial followed by a double-blind comparison with placebo, and then an open-label, long-term protocol. During dose ranging, 8 of 12 patients achieved greater than or equal to 80% suppression of total VPCs (mean 83%) (p less than 0.01 vs single-blind placebo). Paired VPCs were suppressed greater than or equal to 90% and ventricular tachycardia was eliminated in 11 of the 12 patients (p less than 0.01). The effectiveness of propafenone for treatment of VPCs was confirmed during the double-blind trial (p less than 0.05 vs double-blind placebo) and during treatment for 6 months (p less than 0.05 vs initial single-blind placebo). Propafenone prolonged the PR interval by 16% (p less than 0.01 vs single-blind placebo) and the QRS interval by 18% (p less than 0.001). Left ventricular systolic performance decreased as assessed by 2-dimensional echocardiography (p less than 0.01 vs single-blind placebo). Propafenone increased serum digoxin levels in 5 of 5 patients (mean increase of 83%). Side effects included exacerbation of congestive heart failure (1 patient) and conduction abnormalities (2 patients). Thus, propafenone is effective for treatment of total and repetitive VPCs. Although generally well tolerated, the drug reduces left ventricular systolic function and atrioventricular conduction and increases serum digoxin levels.